30 BULLETIN 1380, U. S. DEPARTMENT OF AGRICULTURE 
Hevea, viz, P. foheri and P. meadii, but the latter has not been 
obtained from black-thread. On the other hand, Rutgers in Java 
has shown by inoculations that black-thread, pod-rot, and claret- 
colored canker are all caused by P. faberi. Other investigators have 
obtained varying results in different countries. Petch summarizes 
the evidence as indicating that in the case of Hevea two species of 
Phytophthora are involved. P. meadii causes fruit-rot, leaf-fall, 
and black-thread, and P. faberi causes fruit-rot, leaf-fall, and claret- 
colored canker. The species found on Hevea in the Amazon Valley 
will be considered under " Leaf diseases," p. 33. 
Tapping cuts recently made at the base of trees growing in damp 
soil were occasionally observed to exude a slimy or brownish watery 
excretion somewhat after the manner of the slime flux of oaks in the 
Temperate Zone. The exuded mass attracted flies and beetles and 
supported various grayish and greenish molds. Among these were 
Aspergillus and PenicUliurn species. The tissues of the wound be- 
came black and sodden but did not appear to spread much beyond 
the parts actually affected by the ax. The disturbance is probably 
due t<* infiltration of spore-laden rain water in the cut, and the effect 
is local. 
A moldy rot of tapped surfaces is recorded from the Malay Penin- 
sula with which a species of Sphaeronema is associated. This dis- 
ease, however, is reported to spread to the wood, causing shrinkage 
resulting in large open wounds. A similar disease is recorded from 
Ceylon, but the organism found in association is Phytophthora 
fdbt ri. 
Black moldy rubber excrescences common on tapping cuts are 
described later. 
In connection with the disease of tapping wounds. Akers, in his 
report on rubber in the Amazon Valley, refers to a "cambium rot 
which threatens to exercise a most unfavorable influence in connec- 
tion with the future progress of the rubber industry." He states 
that the disease appears in a most virulent form when the oriental 
tapping methods (herringbone system) are employed. He considers 
this as unfortunate, since this system affords a greater yield of latex 
with no additional labor, thus substantially reducing the ultimate 
cost of production. According to Akers the disease occurs on trees 
tapped with the small ax (machadinho) as well as on trees tapped 
with the gouge on the herringbone system. With the former method 
the (i ionise is neither so apparent nor so destructive, because the 
overhanging flap of cortex covers the incision, and since the coagu- 
lated latex in the cut is not usually collected for scrap the wound 
is protected against atmospheric action. 
From experiments carried on in the districts near the Madeira 
and Purus Rivers and at Manaos in 1913, using different modifica- 
tions of the herringbone system, the rot appeared on the tapped 
surface after about 1 inch of the bark had been removed. The tool 
used was the bent gouge. 
The first sign of the disease is the appearance of the mycelium 
of the fungus in the form of a blue mold on the tapped surface or in 
the cuts made by the ax. The fungus spreads rapidly over the 
tapped surface, affecting the thin layer of cortex over the cambium, 
and later an exudation of a resinous nature appears on the affected 
